| 摘要 |
PURPOSE:To eliminate the work of externally installing resistance elements and thereby to simplify the manufacturing process by a method wherein resistance elements of desired values are created through a proper combination of distribution cells not participating in the construction of a logical circuit. CONSTITUTION:A 1/2 geometrical potential dividing circuit 61 receives an outputted voltages V1 from a 21/n geometrical voltage generating circuit 62 serially connected to the front end thereof. For the generation of voltages arranged in a way of geometrical progression with a common ratio of 1/2 with the voltage V1 as the reference voltage, the voltage the circuit 61 receives is divided by the reference voltage V1, using the group 63 of serially connected potential dividing resistors with values R4, R4, 2R4...2m-1R4 (where m is a positive integer) arranged geometrical progression-wise. A voltage is taken out at an output termianl 65, selected out of the voltage supplied from the points of division via semiconductor switches 64S1, 64S2...64Sm constituting a first switching means 64. A multiplicity of voltages with a common ratio of 1/2 or IEV step reference voltages V3 can be obtained by using a controlling wires group A to select from the semiconductor switches 64S1, 64S2...64Sm. |
